An Evaluation Method for Microgloss Uniformity

Abstract

Microgloss uniformity affects the final image quality of electrophotographic printers. The microgloss is the noise of the micro-gloss differential, and occurs because of either insufficient pressure or toner blistering. Microgloss uniformity evaluation methods have been proposed previously. However, these methods have not been used to establish a standard method. The purpose of this paper is to establish a simple quantitative microgloss evaluation method. The measurement device is composed of a charge-coupled device (CCD) camera and vertically-incident lighting equipment. Because the measurement geometry is 0°/0°, the measuring device is small in size and the camera angle adjustment process is simple. In addition, polarizing filters are inserted into the optical path to suppress any internal diffuse reflected light. The RGB (red-green-blue) image measured by the CCD camera is converted into an L*a*b* image. The L* image is then Fourier transformed to obtain the Wiener spectrum. An evaluation model using Hunter whiteness, a visual characteristic, and the Wiener spectrum was proposed. As a result, the contribution of the evaluation model and the subjective score was 0.94. Because this method is simple, it is expected to find widespread application in the printing industry.